1. Field of the Invention
The invention relates generally to bowling balls, and more specifically to systems and methods of drilling and fitting a bowling ball to a bowler's hand.
2. Discussion of Background Information
The finger and thumb holes in bowling balls have traditionally been drilled with an upright drill press or milling machine, and in some cases with a horizontal boring machine. After drilling, the top edge of the hole is extremely sharp and requires beveling or chamfering in order not to cut the bowler's fingers or thumb and to provide a comfortable bowling grip that does not cause stress, bruising, or irritation of the bowler's hand.
Beveling or chamfering is usually accomplished manually with a three edged knife called a bevel knife. To bevel/chamfer the ball, a ball drilling technician will hold the bevel knife with one sharp edge perpendicular to the edge of the hole, and then begin carving or scraping the hole with the edge of the knife. As the sharp edge of the ball is removed, the technician will continue to scrape, rotating the knife until it becomes tangent to the circumference of the ball. The scraping continues until the edge of the hole has a smooth radius. This process is continued around the entire circumference of the hole. Once the holes are beveled with the bevel knife, the technician may use a high speed sander equipped with a long shank approximately 6″ long and a sanding disk of 1″ to 1.5″ in diameter. The high speed sander is then used to remove irregular knife marks left behind by the bevel knife, and to smooth the bevel and interior walls of the hole. In this process the operator installs the sand paper (usually 80 to 120 grit) on the shank of the sander, turns the sander on, and slowly enters the bowling ball hole, while reciprocating the sander up and down until the desired bevel and/or smoothness is achieved.
Alternatively to using the bevel knife, a technician may use only a high speed sander to bevel the holes. In this method, the operator usually chooses a coarser grit sand paper as described above (e.g., 80 grit) and installs it on the high speed sander shank, then turns on the sander, and slowly inserts the spinning sandpaper disk into the hole, continuously reciprocating the sander up and down until the desired bevel is achieved. This process requires frequent changes of the sandpaper discs as the sandpaper wears out quickly since the sandpaper is removing much more of the bowling ball material than in the bevel knife and high speed sander method. At this point the operator may elect to choose a finer grit sand paper, replacing the coarser grit on the high speed sander, and sand the hole again to produce a smoother surface on the interior of the drilled hole, and the bevel of the hole.
Problems with the traditional methods described above (e.g., bevel knife and/or high speed sander) are that these processes are not conducive to beveling “house balls” (e.g., bowling balls the bowling center provides to their patrons for use when the bowler/patron does not have their own custom fitted bowling ball). Typically, ball drilling technicians achieve only a ⅛″ to ¼″ radius because of the amount of time it takes to scrape each hole, and then sand with the high speed sander, or if using the alternative method, the excessive amount of time it takes to replace the sandpaper frequently. Additionally, since the bevel of each hole is hand crafted, the amount of bevel between holes, and the amount of bevel from ball to ball is inconsistent. Inconsistent bevels from ball to ball feel different in the bowler's hand. This is not desirable by the bowling center proprietor as some bowlers may feel that some balls are comfortable, while other balls are not.